Transient and permanent reproductive dysfunction in fish has been linked to chemicals that disrupt the[unreadable] endocrine system, but the mechanisms involved are unclear. Many endocrine-disrupting chemicals (EDCs)[unreadable] interact with sex hormone receptors by acting as agonists to induce gene expression at inappropriate times[unreadable] or act as antagonists to prevent the normal functioning of the receptors. Other EDCs may act indirectly by[unreadable] altering the processes involved in regulating sex steroid synthesis and metabolism. Poor reproduction and[unreadable] altered plasma hormone levels have been observed in largemouth bass living in ecosystems polluted with[unreadable] organochlorine pesticides (OCPs), including the Superfund site at Lake Apopka and its surrounding muck[unreadable] farms, suggesting that OCP exposure has adversely affected their reproduction.[unreadable] In past research, we have identified three estrogen receptors (a, pi, and (32) in largemouth bass, which[unreadable] exhibit tissue specific expression and respond differently to 17-p-estradiol at the message and activity level.[unreadable] These differences are important to control normal reproductive function. We have evidence that EDCs can[unreadable] alter their normal expression and activity patterns, possibly disrupting reproduction. In addition, we have[unreadable] preliminary evidence that expression of enzymes involved in the synthesis and metabolism of EDCs is[unreadable] affected by the OCPs. The proposed studies will test the central hypothesis that exposure of largemouth bass[unreadable] to concentrations of OCPs found in the Lake Apopka region disrupts endocrine system function by sex[unreadable] hormone receptor mediated and sex hormone receptor independent mechanisms. In this proposal, we have[unreadable] designed a set of interrelated experiments from the organismal level where pleiotropic effects of OCPs can[unreadable] be measured to the cellular level where specific molecular mechanisms of action can be assessed. We are[unreadable] exposing largemouth bass to methoxychlor (and its metabolites), p,p' DDE, dieldrin and toxaphene. Our[unreadable] specific aims include 1: Develop biomarkers of exposure to organochlorinated pesticides in vivo, via the use[unreadable] of microarrays and novel proteomics methodologies; 2: Determine the effect of in vivo OCP exposure on LME[unreadable] steroid synthesis and metabolism; and 3: Evaluate the effects of OCPs on the molecular mechanisms of[unreadable] action of the three estrogen receptors. We plan on using exposures to compounds with known modes of[unreadable] action as controls to determine mode of action specific gene expression patterns against which we will[unreadable] compare the patterns of gene expression changes induced by the OCPs. We will check these pattern[unreadable] changes against reproductive endpoints including the ability of eggs to mature (germinal vesicle breakdown)[unreadable] and sperm function (sperm motility). Fish are useful as sentinels of environmental quality and are perfect[unreadable] models to monitor adverse effects in reproduction caused by contaminants in superfund sites. By[unreadable] extrapolation fish can report on the potential of OCPs to harm human health.